In prior art storage systems, write channel circuitry operation including the magnetic heads were monitored by providing additional test circuits across the heads to determine whether the write channel was operating satisfactorily. The additional electronics would load the head and contribute noise signal so that monitoring was subject to error.
When more than one recording channel is employed in a system, and each channel has its own test circuits coupled across the magnetic heads, the probability of error increases as well as the cost and maintenance of the additional test circuits. Further problems arise when thin film heads are used as the read/write elements. In such event, the inductance of the wire leads attached to the thin film is greater than the relatively low inductance of the thin film head itself. Thus, inductive measurements for checking operability of the multiplicity of thin film heads that may be used in data storage systems do not provide accurate testing results. Apparently, it would be desirable to provide accurate means for checking operability of write channels and magnetic heads of the thin film type in a simplified and inexpensive way.